Apparatus for damping pressure fluctuations in pulp suspension flow of paper machines

Abstract

An apparatus for damping pressure fluctuations in the pulp-suspension flow of a paper machine includes a pipe system which delivers the pulp suspension to a headbox and in the interior of which the pulp suspension flows toward the headbox. A portion of the pipe system is surrounded by a gas, such as air, which is under pressure and which is situated within a suitable enclosure. This portion of the pipe system is formed at least in part by an elastic wall structure, the inner surface of which engages the pulp-suspension flow and the outer surface of which is exposed to the gas under pressure. Thus, the elastic wall structure changes its configuration or geometry due to pressure fluctuations in the pulp-suspension flow while the gas under pressure which acts through the elastic wall structure on the pulp suspension serves to damp the pressure fluctuations.

What is claimed is: 
     
       1. In an apparatus for damping pressure fluctuations in a pulp-suspension to a headbox with the suspension flowing along the interior of a pipe system, enclosure means having a hollow interior for enclosing in said hollow interior a gas such as air at a pressure greater than atmospheric pressure, said pipe system including an elastic wall means formed of a substantially unstretchable material having substantial flexibility, said wall means having an inner surface defining part of the interior of said pipe system for engaging pulp suspension flowing through the interior of said pipe system and an outer surface exposed in the hollow interior of said enclosure means to the gas under pressure therein, said elastic wall means responding to an increase in the pressure of the suspension with respect to the pressure of the gas to increase the cross section of said suspension flow where the suspension engages said elastic wall means and responding to a decrease in the pressure in said enclosure means for decreasing said cross section so that through said elastic wall means pressure fluctuations in the flowing pulp suspension will be damped, said enclosure means having an outer wall surrounding the hollow interior thereof, said elastic wall means having an outer peripheral portion fixed to said outer wall of said enclosure means and surrounded thereby and an inner peripheral portion situated inwardly of and surrounded by said outer wall of said enclosure means, said pipe system including a pipe fixed at one end to said inner peripheral portion of said elastic wall means and extending therefrom through the interior of said enclosure means, and said pipe system including a second pipe having an end connected with said outer peripheral portion of said elastic wall means, said pipes respectively directing the suspension into and out of said enclosure means while exposing the suspension to the pressure of the gas in said enclosure means through said elastic wall means. 
     
     
       2. The combination of claim 1 and wherein said pipe system includes in its interior adjacent but spaced from said elastic wall means a baffle means defining with said elastic wall means an interior space of said system through which the suspension flows substantially radially between said peripheral portions of said elastic wall means. 
     
     
       3. In an apparatus for damping pressure fluctuations in a pulp-suspension flow in a paper machine, a pipe system for delivering the pulp suspension to a headbox with the suspension flowing along the interior of the pipe system, enclosure means having a hollow interior for enclosing in said hollow interior a gas such as air at a pressure greater than atmospheric pressure, said pipe system including an elastic wall means having an inner surface defining part of the interior of said pipe system for engaging pulp suspension flowing through the interior of said pipe system and an outer surface exposed in the hollow interior of said enclosure means to the gas under pressure therein, said elastic wall means responding to an increase in the pressure of the suspension with respect to the pressure of the gas for expanding to increase the cross section of said suspension flow where the suspension engages said elastic wall means and responding to a decrease in the pressure of the suspension with respect to the gas pressure in said enclosure means for decreasing said cross section so that through said elastic wall means pressure fluctuations in the flowing pulp suspension will be damped and wherein said pipe system has a portion adjacent said enclosure means which is movable with respect thereto in connection with headbox adjustment, said elastic wall means including a tubular portion for surrounding the pulp-suspension flow and having an end fixed with said portion of said pipe system for movement therewith while forming an extension thereof so that the pulp suspension flows without interruption in the interior of said elastic wall means and said portion of said pipe system, and flexible bellows means surrounding said elastic wall means at the region where it is connected with said portion of said pipe system, said bellows means being fixed at one end together with said elastic wall means to said portion of said pipe system and at an opposite end directly to said enclosure means while being spaced from and surrounding said elastic wall means. 
     
     
       4. The combination of claim 3 and wherein said bellows means includes a plurality of endless convolutions of substantially U-shaped cross section situated one next to the other while surrounding and spaced from said elastic wall means and having a configuration conforming generally to the cross-sectional configuration of an elastic wall means at least at the portion thereof surrounded by said bellows means, said convolutions having hollow interiors which are directed toward said elastic wall means, and said convolutions having side wall portions engaging each other, and a plurality of rings engaging and fixing said side wall portions of said convolutions to each other while also surrounding and being spaced from said elastic wall means and having a configuration corresponding generally to the cross-sectional configuration of said elastic wall means. 
     
     
       5. The combination of claim 3 and wherein said portion of said pipe system has, at its end which is fixed to said bellows means and elastic wall means, a flange which extends outwardly from said portion of said pipe system in a plane substantially parallel to the direction of adjusting movement of said portion of said pipe system, slide-plate means slidably engaging said flange and being parallel thereto, and limiting means normally spaced from said flange while being fixed to said enclosure means and carrying said slide-plate means and extending from said enclosure means substantially parallel to the direction of suspension flow for limiting the extent of adjustable movement of said portion of said pipe system. 
     
     
       6. The combination of claim 3 and wherein an elastic connection means is situated at an end of said enclosure means opposite from said bellows means for connecting said elastic wall means to said enclosure means while facilitating the mounting of said elastic wall means in a position extending through said enclosure means. 
     
     
       7. The combination of claim 6 and wherein said elastic connection means includes a bellows means identical with that which connects said elastic wall means to said portion of said pipe system. 
     
     
       8. The combination of claim 3 and wherein said bellows means has a hollow interior communicating with the hollow interior of said enclosure means while surrounding said elastic wall means.